JP5000854B2 - Continuous production method of aqueous polyurethane dispersion - Google Patents

Description

  The present invention relates to a continuous process for the production of aqueous (or aqueous) polyurethane dispersions (dispersions or dispersions) based on aliphatic and / or aromatic polyisocyanates.

  From the prior art, two batch processes are essentially known as a process for producing aqueous polyurethane dispersions on a commercial scale: the acetone process and the prepolymer mixing process. Production of dispersions based on aliphatic polyisocyanates is fairly easily achieved using both methods for the proper reactivity of the aliphatic polyisocyanates. Production of dispersions based on aromatic polyisocyanates is generally carried out using the acetone method or the ketimine method. This is because both excessive foaming in the dispersion process caused by the isocyanate-water reaction is prevented. In WO81 / 02894, other methods are used to obtain dispersions based on aromatic polyisocyanates (PIC). The reactive PIC group is reacted with a blocking agent that can be separated again. As a result, foaming is only mild or does not occur at all. The disadvantages of this method are, as seen in the ketimine method, on the one hand in the additional blocking step and on the other hand in the low molecular weight blocking agent which must remain in the system or have to be removed in an additional step.

  EP-A-0220000 describes the production of aromatic dispersions by the prepolymer mixing method. However, the examples show that an external emulsifier is always required for the production process. It will later remain in the coating made from the dispersion, resulting in disadvantages known to those skilled in the art. Furthermore, the prepolymer is neutralized indirectly. That is, the tertiary amine required to neutralize the carboxyl group is added to the initial water. Here, direct neutralization results in a significant reduction of NCO in the prepolymer, well below the theoretical NCO content. Furthermore, it is almost impossible to replace the hydrazine used as a chain extender amine for other amines reactive towards isocyanates. Finally, the dispersion obtained on the basis of EP-A-0220000 has a solids content of only 30% by weight.

  For the continuous production of aqueous polyurethane dispersions, for example, the process according to WO 98/41552 is known. In this method, the dispersion is produced using a mechanically driven disperser (or disperser), so it is prone to failure and is usually added with an external emulsifier.

  EP-A 0 303 907 also discloses a continuous process by which aqueous polyurethane dispersions can be produced. A preferred method is to feed weighed water into the high viscosity prepolymer at high speed to homogenize the heterogeneous mixture or disperse the (pre) polymer in the mixing tube. Although a very useful method per se, the disadvantage of this method is that when processing high viscosity prepolymers, the service life (or lifetime) of the system is increasingly reduced.

  It is an object of the present invention to provide a continuous process for producing an aqueous aliphatic polyurethane dispersion and an aqueous aromatic polyurethane dispersion that do not have the disadvantages described above. In particular, the process should also be able to provide polyurethane dispersions based on aromatic polyisocyanates and to process high viscosity prepolymers. Furthermore, the method should be characterized by a high service life on the order of 10 hours or more.

The present invention
a) a step of producing an aqueous pre-emulsion by mixing a polyurethane prepolymer containing a hydrophilic group and / or a latent hydrophilic group and water with a mixing nozzle (or a mixing nozzle), B) homogenizing (homogenizing or homogenizing) the pre-emulsion from step a) with a step of (or pouring) in water, and b) a multi-step homogenizing nozzle. To provide a continuous process for the production of an aqueous polyurethane dispersion based on at least one aliphatic and / or aromatic polyisocyanate, comprising the step of forming an emulsion.

  The present invention is also directed to a substrate coated with a coating comprising an aqueous polyurethane dispersion produced according to the method described above.

BEST MODE FOR CARRYING OUT THE INVENTION

  All numbers or expressions relating to the amounts of ingredients, reaction conditions, etc. used in the description and claims are used in all cases where the term “ It should be understood that it is modified by “about”.

The present invention provides a continuous process for the preparation of an aqueous polyurethane dispersion based on at least one aliphatic and / or aromatic polyisocyanate, which is characterized by the following steps:
a) A process for producing an aqueous pre-emulsion by mixing a polyurethane prepolymer containing hydrophilic groups and / or latent hydrophilic groups with water at a mixing nozzle, wherein the polyurethane prepolymer is put into water (or injected). ) Process;
b) Forming the emulsion by homogenizing the pre-emulsion from step a) with a multi-stage homogenizing nozzle (or homogenizing nozzle).

  The starting material of the process of the present invention for continuously producing an aqueous polyurethane dispersion is a polyurethane prepolymer. The preparation of solvent-containing or solvent-free polyurethane prepolymers suitable for the process according to the invention is carried out in a manner known from the prior art. Various methods are fully described in the prior art.

  The method described in EP-A 0304718 can be mentioned by way of example. However, the production of polyurethane prepolymers is not limited to the method described in EP-A 0304718.

  To make the prepolymer, a molar excess of diisocyanate is often initially charged to the reactor, after which diols and polyols containing active hydrogen atoms are added in the presence or absence of a solvent. In general, a polyol mixture consisting of diols, triols or polyols of higher molecular weight (400-6000 g / mol) and lower molecular weight (62-400 g / mol) contains groups reactive towards isocyanate groups. There are also compounds that can be hydrophilic, ionic and / or nonionic and / or hydrophilic. These ensure the dispersibility of the polymer. The reaction is usually carried out at a temperature of 40-120 ° C. until a constant NCO content is obtained. Conventional catalysts in polyurethane chemistry can also be used to promote the NCO-OH reaction. Converting a potential hydrophilic group to a hydrophilic group that causes dispersibility in water can be achieved by setting an appropriate compound (eg, in the case of a carboxyl group-functional prepolymer) after or before setting the NCO content. Is usually carried out by adding a base or, in the case of a prepolymer containing tertiary amino groups, a component or acid that causes quaternization.

  Converting a component that can be hydrophilic into a hydrophilic form, for example using amine neutralization, takes place online and in a reactor for prepolymer production during the continuous process of the invention. be able to. If this step is performed online, a sufficient amount of functional groups to cause conversion to the ionic form before mixing the prepolymer with water or during pre-emulsion production of step a) of the process of the invention. This can be done by adding to the water (referred to as dispersed water).

  Prior to producing the aqueous pre-emulsion based on step a), it is preferred that the prepolymer is continuously reacted in a mixing nozzle with at least one component that causes the conversion of latent ionic groups to ionic form. .

  Aliphatic or aromatic polyisocyanates or mixtures of aliphatic and aromatic polyisocyanates can be used in the process of the present invention.

As the aliphatic polyisocyanate for producing the polyurethane prepolymer, it is preferable to use a diisocyanate of the formula R ¹ (NCO) ₂ . Here, R ¹ is an aliphatic hydrocarbon group having 4 to 12 carbon atoms, an alicyclic hydrocarbon group having 6 to 15 carbon atoms, or an araliphatic hydrocarbon group having 7 to 15 carbon atoms. Indicates. Examples of these preferred diisocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, α, α, α ′, α′-tetramethyl-m- or p-xylylene diisocyanate; 1-isocyanato-3,3,5-trimethyl There are -5-isocyanatomethylcyclohexane (isophorone diisocyanate) and 4,4'-diisocyanatodicyclohexylmethane and mixtures of the aforementioned diisocyanates.

As aromatic polyisocyanate for producing the prepolymer, diisocyanates of the formula R ² (NCO) ₂ are used. Here, R ² represents an aromatic hydrocarbon group having 6 to 15 carbon atoms. Examples of these preferred diisocyanates are 4,4′-diisocyanatodiphenylmethane, 2,4′-diisocyanatodiphenylmethane, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene or these diisocyanates. It is a mixture.

  Conventional components used in the production of polyurethanes are used as higher molecular weight polyols having a molecular weight of 400 to 6000. They have an OH number of 1.8-5, preferably 1.9-3, particularly preferably 1.93-2.0. They are, for example, polyesters, polyethers, polycarbonates, polyester carbonates, polyacetals, polyolefins, polyacrylates and polysiloxanes. Polyethers based on polyester, propylene oxide or tetrahydrofuran, polyester carbonates and polycarbonate α, ω-diols are preferably used.

  Suitable short chain diols and polyols are those having a molecular weight of less than 400. Conventional diols in polyurethane chemistry can be used as diols, such as ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol. 2-ethyl-1,3-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 2,4-dimethylpentanediol, 2-ethyl-3-propyl-1,5-pentanediol, 2,2,4 -Trimethylpentanediol, cyclohexanedimethanol or a mixture of such diols. For example, short-chain polyols such as trimethylolpropane, glycerol, hexanetriol, pentaerythritol, and N, N ′, N ″ -tris (2-hydroxyethyl) isocyanurate are also present in some cases where the prepolymer is stirrable. In quantity, can be added.

Suitable ionic or potentially ionic and nonionic compounds are those that have at least one group that is reactive towards the NCO group. Suitable compounds are, for example, mono- and dihydroxycarboxylic acids, mono- and diaminocarboxylic acids, mono- and dihydroxysulfonic acids, mono- and diaminosulfonic acids, mono- and dihydroxyphosphonic acids or mono- and diaminophosphonic acids and their Salts such as dimethylolpropionic acid, dimethylolbutanoic acid, hydroxypivalic acid, N- (2-aminoethyl) -β-alanine, 2- (2-aminoethylamino) ethanesulfonic acid, ethylenediamine propylsulfonic acid or Ethylenediamine butylsulfonic acid, 1,2- or 1,3-propylenediamine-β-ethylsulfonic acid, lysine or 3,5-diaminobenzoic acid. EP-A-0916647 example 1 hydrophilizing agent, alkali and / or ammonium salt thereof, adduct (or adduct) of sodium sulfite and butene-2-diol-1,4, polyether sulfonate, 2-butenediol And propoxylated with an adduct of NaHSO ₃ (see, for example, pages 5 to 9 of DE-A 2446440, formulas I to III) and building blocks that can be converted into cationic groups such as N-methyldiethanolamine Etc. are also suitable.

  Nonionic hydrophilic compounds such as polyoxyalkylene ethers having at least one hydroxyl group or amino group can be used as part of the hydrophilizing component or as a separate hydrophilizing component. These polyethers contain 30 to 100% by weight of building blocks derived from ethylene oxide.

  The prepolymer exhibiting latent ionic groups is converted to an ionic form prior to producing the pre-emulsion of step a) by reacting with appropriate components. The prepolymer having a carboxyl group or a sulfonic acid group is converted to an ionic or water-soluble group by adding a basic compound. Amino groups are converted to ionic, water-soluble groups by protonation / quaternization.

  If the prepolymer has a sufficient amount of polyethylene oxide chains or sulfonate groups, it can form a resin that can be dispersed without any other additives, even without co-hydrophilization using the above components. it can.

  The acid groups are neutralized with a tertiary amine that is inert with respect to the isocyanate groups. During subsequent curing, the film (or film) may be left completely or partially. Examples of these compounds are ammonia, ammonium carbonate or bicarbonate, trimethylamine, triethylamine, tributylamine, diisopropylethylamine. Amines containing groups that are reactive towards isocyanates, such as dimethylethanolamine, diethylethanolamine, triethanolamine, no longer leave membranes when bonded to the polymer matrix and are less preferred to use. Furthermore, alkali and alkaline earth hydroxides or the corresponding carbonates are also less preferred.

  In the case of cationic groups, dimethyl sulfate, phosphoric acid or succinic acid may be used. In addition, quaternizing agents such as 1,4-dichlorobutene can be used. Converting potentially ionic groups to ionic form is preferably done in a mixing nozzle, but may be done in bulk for NCO prepolymers based on aliphatic polyisocyanates.

  The production of the aqueous pre-emulsion in step a) takes place in a mixing nozzle. Examples of mixing nozzles that can be used are smooth-jet nozzles, fan-spray nozzles, annular nozzles, ring-shaped (or ring-shaped) nozzles, perforated nozzles or counter-jets. -jet) Nozzle. It is preferred to use a mixing nozzle that operates in a manner similar to the pre-emulsification in a jet disperser known from DE 19510651A. The prepolymer feed is optionally temperature controlled.

  The preparation of the pre-emulsion in step a) using a mixing nozzle is carried out at a differential pressure (or pressure difference) of 0.1 to 100 bar, preferably 0.2 to 50 bar, particularly preferably 0.5 to 20 bar.

  To produce the aqueous pre-emulsion of step a), sufficient water is added to form an oil in water emulsion. The ratio of the polyurethane prepolymer to water is preferably 70:30 to 20:80 parts by weight, more preferably 66:34 to 30:70 parts by weight, and 50:50 to 35:65 parts by weight. It is particularly preferred that

  In accordance with the present invention, the polyurethane prepolymer is placed (or injected) in the water of step a). This method has the advantage of a longer useful life (life or service life) compared to other methods in which water is placed in the polyurethane prepolymer.

  In a preferred embodiment of the present invention, the temperature of the prepolymer is 10 ° C to 100 ° C, preferably 15 ° C to 80 ° C, particularly preferably 20 ° C to 70 ° C. The temperature of the dispersed water is 5 ° C to 95 ° C, preferably 10 ° C to 85 ° C, particularly preferably 20 ° C to 60 ° C. The processing temperature of the prepolymer determines the viscosity of the resin, which is 500 to 100,000 mPa · s, preferably 1,000 to 70,000 mPa · s, particularly preferably 2,000 to 40,000 mPa · s. .

  Based on step b) of the process of the present invention, an emulsion is produced by homogenizing the pre-emulsion from step a). Homogenization is performed with a multi-stage homogenizing nozzle. 2 to 20 stages are preferably used, and 3 to 15 stages are particularly preferably used. Examples of homogenizing nozzles that can be used are flat nozzles, notched nozzles, knife edge nozzles or counter-jet dispersers (or dispersers). A jet disperser is preferably used as a homogenizing nozzle. For example, a jet disperser known from DE19510651A can be used as a jet disperser.

  Producing the emulsion from the pre-emulsion by homogenization based on step b) using a multi-stage homogenizing nozzle is 1 to 200 bar, preferably 3 for the sum of all stages of the multi-stage homogenizing nozzle. It is carried out at a differential pressure of -100 bar, particularly preferably 5-60 bar.

  In a preferred embodiment of the process according to the invention, in step c), the emulsion prepared in step b) containing NCO groups is at least partially reacted with at least one amine having reactivity with isocyanate groups. . Here, the amount of the amine is such that the chain extension is about 40 to 125%, preferably 50 to 100%, particularly preferably about 60 to 90%.

  Suitable amines for this purpose are as follows: amino alcohols with molecular weights up to 400 and mono-, di-, tri- and / or tetraamino functional substances such as ethylenediamine, 1,2- And 1,3-diaminopropane, 1,3-, 1,4- and 1,6-diaminohexane, 1,3-diamino-2,2-dimethylpropane, 1-amino-3,3,5-trimethyl- 5-aminoethylcyclohexane (IPDA), 4,4′-diaminodicyclohexylmethane, 2,4- and 2,6-diamino-1-methylcyclohexane, 4,4′-diamino-3,3′-dimethyldicyclohexylmethane, 1,4-bis (2-aminopropan-2-yl) -cyclohexane, polyamines such as ethylenediamine, 1,2- and 1,3-di Minopropane, 1,4-diaminobutane, 1,6-diaminohexane, isophoronediamine, a mixture of isomers of 2,2,4- and 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, diethylenetriamine 1,3- and 1,4-xylylenediamine, α, α, α ′, α′-tetramethyl-1,3- and 1,4-xylylenediamine and 4,4-diaminodicyclohexylmethane, aminoethanol , Diethanolamine or a mixture of these compounds. Hydrazine, hydrazine hydrate, substituted hydrazines such as N-methylhydrazine, N, N′-dimethylhydrazine and their homologs, adipic acid, β-methyladipic acid, sebacic acid, hydroacrylic acid and terephthalic acid Dihydrazide, semicarbazide alkylene hydrazide such as β-semicarbazide propionic acid hydrazide (eg DE-A1770591), semicarbazide alkylene carbazic ester such as 2-semicarbazide ethylcarbazic ester (eg DE-A1918504) or aminosemicarbazide Compounds such as β-aminoethyl semicarbazide carbonate (eg DE-A1902931) are also suitable as diamines within the meaning of the present invention. The partial use of monofunctional amines having no other reactive groups in the NCO group, such as butylamine and higher homologues, is also possible.

  However, in other embodiments, the addition of chain extender can be omitted, so that chain extension is performed exclusively with water.

  The reaction with the amine in step c) can be carried out batchwise using separate reactors or continuously with a mixing nozzle, for example. A continuous reaction in the mixing nozzle is preferred. Examples of mixing nozzles that can be used are smooth jet nozzles, fan-spray nozzles, annular nozzles, ring-shaped (or ring-shaped) nozzles, perforated nozzles or counter-jet nozzles. It is preferred to use a mixing nozzle with a jet disperser known from DE 195 0651 A, which functions similarly to pre-emulsification.

  The aqueous polyurethane dispersion produced by the process of the present invention has an average particle size of 25 to 600 nm, preferably 30 to 300 nm, particularly preferably 35 to 250 nm. The solids content (or solid content) of the polyurethane dispersion is in the range of 30 to 65% by weight, preferably 35 to 60% by weight and particularly preferably 37 to 50% by weight.

  The essential advantage of the method of the present invention is continuous operation. For the process of the invention comprising steps a) and b), only one stirred tank is required to produce the NCO prepolymer. Chain extension can be carried out batchwise in other reactors, but chain extension is preferably carried out continuously, and no second stirred tank is required. In a comparable batch process known in the prior art consisting of producing a polyurethane prepolymer and subsequently producing a polyurethane dispersion, two stirred tanks are usually required (inverse process).

  The process according to the invention is particularly advantageous for polyurethane dispersions based on aromatic polyisocyanates. Although a high solids content of at least 35% by weight can be achieved, less than 30% by weight solids are obtained using discontinuous methods known from the prior art.

  Furthermore, in the process of the present invention, it is not necessary to use external emulsifiers, but such dispersions prepared from the prior art partially or exclusively stabilized by ionic and / or nonionic external emulsifiers are also present in the present invention. Inventive methods include. Furthermore, all known amines can be used as chain extenders. Thus, it is easy to use a wide range of dispersions based on aromatic polyisocyanates having a wide variety of properties.

  In order to mix the components, for example to mix the polyurethane prepolymer with water and to homogenize the pre-emulsion, a mixing nozzle, preferably a jet disperser (it has no moving parts) The use of is also an advantage of the method of the present invention. They are therefore less prone to failure and require less maintenance.

  Compared with the methods known from the prior art, the method according to the invention has a longer service life. The method of the invention guarantees continuous and trouble-free operation on the order of 10 hours.

  The present invention also provides a substrate that is coated with a coating using an aqueous polyurethane dispersion produced by the method of the present invention.

Examples of these substrates are substrates based on wood, metal, plastic, paper, leather, fabric (or cloth), felt, glass or inorganic (or mineral) components. The substrate may be coated directly with a coating based on an aqueous polyurethane dispersion produced by the method of the present invention, or one or more other coats of any type The substrate may be initially fed.
The main aspects of the present invention are described below.
1.
a) A step of producing an aqueous pre-emulsion by mixing a polyurethane prepolymer containing a hydrophilic group and / or a latent hydrophilic group and water with a mixing nozzle, wherein the polyurethane prepolymer is put into water. ,as well as
b) Forming the emulsion by homogenizing the pre-emulsion from step a) with a multi-stage homogenizing nozzle.
A process for the continuous production of an aqueous polyurethane dispersion based on at least one aliphatic and / or aromatic polyisocyanate, comprising:
2.
The process of claim 1, further comprising the step c) of at least partially reacting the emulsion comprising free NCO groups from step b) with at least one amine reactive with isocyanate groups. .
3.
3. The method according to 2 above, wherein the reaction with the amine in step c) is carried out continuously with a mixing nozzle.
4).
The process according to 1 above, wherein the preparation of the pre-emulsion in step a) is carried out at a differential pressure of 0.1 to 100 bar.
5.
Process according to 1 above, wherein the formation of the emulsion of step b) is carried out at a differential pressure of 1 to 200 bar.
6).
The process according to 1 above, wherein 2 to 20 steps are used for the homogenization of step b).
7).
The method according to 1 above, wherein a jet disperser is used as the homogenizing nozzle in step b).
8).
The method according to 1 above, wherein the jet disperser is used as a mixing nozzle in step a).
9.
The method according to 1 above, wherein the temperature of the polyurethane prepolymer in step a) is from 10 ° C to 100 ° C.
10.
The method according to 1 above, wherein the temperature of the water in step a) is 5 ° C to 95 ° C.
11.
A substrate coated with a coating film comprising an aqueous polyurethane dispersion produced by the method according to 1 above.
12
The process according to 1 above, wherein the formation of the emulsion of step b) is carried out at a differential pressure of 3 to 100 bar.
13.
Process according to 1 above, wherein the formation of the emulsion of step b) is carried out at a differential pressure of 5 to 60 bar.
14
The process according to 1 above, wherein the preparation of the pre-emulsion in step a) is carried out at a differential pressure of 0.2 to 50 bar.
15.
The process according to 1 above, wherein the preparation of the pre-emulsion in step a) is carried out at a differential pressure of 0.5 to 20 bar.
16.
The method of claim 2, wherein the jet disperser is used as a homogenizing nozzle in step b).
17.
4. A process according to 3 above, wherein the jet disperser is used as a homogenizing nozzle in step b).
18.
The method according to 2 above, wherein the temperature of the polyurethane prepolymer in step a) is from 10 ° C to 100 ° C, and the temperature of the water in step a) is from 5 ° C to 95 ° C.
19.
The method according to 3 above, wherein the temperature of the polyurethane prepolymer in step a) is from 10 ° C to 100 ° C, and the temperature of the water in step a) is from 5 ° C to 95 ° C.
20.
A substrate coated with a coating film comprising an aqueous polyurethane dispersion produced by the method described in 2 above.
21.
A substrate coated with a coating film comprising an aqueous polyurethane dispersion produced by the method according to 3 above.

Production of OH component A:
Along with 2.4 g of dibutyltin oxide, 3200 g of castor oil (or castor oil) and 1600 g of soybean oil were weighed into a 5 liter reactor fitted with a reflux condenser. A nitrogen stream (5 liters / hour) was passed through the reactants. The temperature was raised to 240 ° C. within 140 minutes. After 4 hours at 240 ° C., the mixture was cooled. The OH value was 109 mgKOH / g, and the acid value was 3.2 mgKOH / g.

Comparative example:
339 g poly-THF (MG2000, BASF AG, Ludwichshafen, Germany), 248 g OH component A, 70 g dimethylolpropionic acid, 34 g 1,6-hexanediol and 179 g N- Methylpyrrolidone was heated to 70 ° C. and stirred until a clear solution was formed. 516 g of Desmodur® W (Bayer, Reefelkusen, Germany) was then added and the mixture was heated to 100 ° C. Stirring was continued at this temperature until the NCO content reached 4.6%. The mixture was then cooled to 70 ° C. and 37 g of triethylamine was added. 500 g of this solution was dispersed in 666 g of water having an initial temperature of 30 ° C. and stirred vigorously.

After dispersion, stirring was continued for 5 minutes. 5.5 g hydrazine hydrate and 8.8 g ethylenediamine solution in 74 g water were then added within 5 minutes. In order to complete the reaction of the isocyanate groups, stirring was continued at 45 ° C. until no more NCO was detected in the IR spectrum. After cooling to 30 ° C., the mixture was filtered using a Seitz T5500 filter.
Comparative polyurethane dispersion property data:
Average particle size (or dimensions): 58 nm (laser correlation spectroscopy (LCS), or LCS)
pH: 7.8
Solid content (or solid content): 36.0% by weight

Example 1: NCO prepolymer 1
Heat 339 g of polyTHF (MG2000, BASF, Ludwigshafen, Germany), 248 g of OH component A, 70 g of dimethylolpropionic acid, 34 g of 1,6-hexanediol and 179 g of N-methylpyrrolidone to 70 ° C. And stirred until a clear solution was formed. 516 g of Desmodur® W (Bayer, Leverkusen, Germany) was then added and the mixture was heated to 100 ° C. Stirring was continued at this temperature until the NCO content reached 4.6%. Finally, the mixture was cooled to 70 ° C. and 37 g of triethylamine was added.

  Further processing of the prepolymer produced in the dispersion apparatus was performed as shown in FIG. Using the gear pump 3, the prepolymer 1 was put into the mixing nozzle 6 at a mass flow rate of 10 kg / hour. Water 2 was passed through heat exchanger 5 and into mixing nozzle 6 using a piston diaphragm pump 4 at a mass flow rate of 9 kg / hour. The mixing nozzle had a hole 10 having a diameter of 2 mm and a mixing zone 11 having a diameter of 9 mm and a length of 200 mm (see FIG. 2). The obtained pre-dispersion 9 was homogenized with six jet dispersers 7. Each of the jet dispersers had two holes 13 with a diameter of 0.8 mm (see FIG. 3). The temperature of the prepolymer feed 1 was 84 ° C. When operating the apparatus, the water temperature was adjusted to 80 ° C. using the heat exchanger 5, and then the temperature was lowered to 46 ° C. after the jet disperser 7 in a steady state. . The pressure drop of the jet disperser 7 was 17 bar.

  Dispersion 12 was cooled to 29 ° C. with heat exchanger 8. This was followed by the addition of 176 g of chain extender solution to 2330 g of dispersion 12 in a glass container (not shown) with stirring. The following were used as chain extender solutions: 11 g hydrazine hydrate and 17.6 g ethylenediamine in 149 g water. After cooling to 30 ° C., the mixture was filtered using a Seitz T5500 filter.

Characteristic data for the polyurethane dispersion of Example 1:
Average particle size: 50 nm (laser correlation spectroscopy, LCS)
pH 8.0
Solid content: 38.6% by weight

Example 2: NCO prepolymer 2
2309.0 g of Aclaim Polyol 2200 (Acclaim Polyol 2200, molecular weight about 2000 g / mol, Bayer, Lefelkusen, Germany), 276.4 g of dimethylolpropionic acid and 154.7 g of 1,6-hexanediol And dehydrated at 110 ° C. under reduced pressure. After reducing the pressure with nitrogen gas, 1064 ml of N-methylpyrrolidone was added and homogenized at 70 ° C. The polyol mixture was then cooled to ambient temperature and placed in a receiver containing 1043.0 g of Desmodor® T80 (Bayer, Leverkusen, Germany) over 1 hour. After all the polyol mixture is added, until the NCO content reaches 2.5% (theoretical NCO content is 2.5%) (viscosity η = 20.6 Pa · s (23 ° C.), D = 40 s ^{− 1} ), stirring was continued at 60 ° C.

  Further processing of the prepolymer produced in the disperser was performed as shown in FIG. Using the gear pump 3, the prepolymer 1 was transferred into the mixing nozzle 16 at a mass flow rate of 12 kg / h.

  A neutralized amine solution 14 consisting of 440.6 parts of triethylamine and 511 parts of N-methylpyrrolidone using a piston pump 15 at a mass flow rate of 1.2 kg / h and a hole 22 having a diameter of 0.3 mm and a diameter of 4 mm. And transferred to a mixing nozzle 16 having a hole 24 (see FIG. 5). The mixture 21 was then fed through three jet dispersers 7 each having four holes 13 each having a diameter of 2.1 mm (as shown in FIG. 3). Thereafter, the mixture was fed into the mixing nozzle 6. Water 2 is fed at a mass flow rate of 15 kg / h through a heat exchanger 5 into a mixing nozzle 6 having a hole 10 having a diameter of 2 mm and a mixing zone 11 having a diameter of 9 mm and a length of 200 mm using a piston diaphragm pump 4. (See FIG. 2). The resulting pre-emulsion 9 was homogenized using six jet dispersers 7 (see FIG. 3) each having four holes 13 with a diameter of 1.2 mm.

  The temperature of the prepolymer feed 1 was 33 ° C. The water temperature was adjusted using the heat exchanger 5, and after the jet disperser 7, the temperature was 37 ° C. in a steady state. The pressure drop based on the jet disperser 7 was 12 bar. The dispersion 12 was cooled to 23 ° C. by the heat exchanger 8 and supplied to the mixing nozzle 20. A chain extender solution 18 consisting of 148.9 parts ethylenediamine and 1645.6 parts water, using a piston pump 19, has a hole 10 with a diameter of 0.3 mm and a mixing zone 11 with a diameter of 9 mm and a length of 100 mm. It added to the mixing nozzle 20 (refer FIG. 2).

Characteristic data of polyurethane dispersion of example 2 Average particle size: 73 nm (Laser Correlation Spectroscopy, LCS)
pH: 7.5
Solid content: 37%

Example 3: NCO prepolymer 3
4643 g PE225B (adipic acid ester based on 1,6-hexanediol, OH number = 47 mg KOH / g, Bayer, Leverkusen, Germany) and 580 g of dimethylolpropanoic acid were reduced in pressure at 110 ° C. for 1 hour. Dehydrated. Thereafter, 1292 g of N-methylpyrrolidone was added to the polyol mixture and stirred until a clear solution was obtained. The mixture was then cooled to 60 ° C. and 3938 g of isophorone diisocyanate was added over 20 minutes. After the exothermic reaction had subsided, the mixture was gradually cooled to 70 ° C. and 744 g of 1,6-hexanediol was added quickly. It cooled so that reaction temperature might not exceed 100 degreeC. After the NCO content of the resin mixture reached 4.0%, a prepared solution of 311 g of N-methylpyrrolidone and 358 g of trimethylamine was added and mixed uniformly.

  Further processing of the prepolymer produced in the disperser was carried out as shown in FIG. 6: Prepolymer 1 was transferred to the mixing nozzle 16 with a gear pump 3 at a mass flow rate of 12 kg / h. Water 2 has a mass flow rate of 12 kg / h and has a hole 22 with a diameter of 1.8 mm and a hole 24 with a diameter of 2.2 mm (as shown in FIG. 5) through the heat exchanger 5 using the piston diaphragm pump 4. It moved to the mixing nozzle 16. The resulting pre-dispersion 21 was homogenized using six jet dispersers 7 (see FIG. 3) each having four holes with a diameter of 1.2 mm. The temperature of the prepolymer feed 1 was 80 ° C. The water temperature was adjusted to 80 ° C. during operation of the apparatus using the heat exchanger 5, and then lowered to a range where the temperature became 55 ° C. in a steady state after the jet disperser 7. The pressure drop based on the jet disperser 7 was 10 bar. The dispersion was placed in the mixing nozzle 26. A chain extender solution 18 consisting of 168 parts ethylenediamine and 1346 parts water is passed through a piston pump 19 at a mass flow rate of 1.5 kg / h with a hole 22 having a diameter of 0.3 mm and a hole 24 having a diameter of 2.2 mm. It was placed in a mixing nozzle 26 (as shown in FIG. 5). After the mixing nozzle 26, a counter pressure of 6 bar was applied to the process using a 0.6 mm diameter diaphragm.

Characteristic data for the polyurethane dispersion of Example 3:
Average particle size: 54 nm (Laser Correlation Spectroscopy, LCS)
pH 7.2
Solid content: 40%

  While the invention has been described in detail for purposes of illustrating the invention, such detailed description is solely for such purposes and is not limited by the scope of the claims. It should be understood that various changes can be made by those skilled in the art without departing from the spirit and scope of the invention.

FIG. 1 shows a flow chart of the method according to the invention for dispersing an aliphatic prepolymer with batch chain extension. FIG. 2 shows one embodiment of a mixing nozzle used to produce a pre-emulsion. FIG. 3 shows an embodiment of a homogenizing nozzle used to homogenize the pre-emulsion. FIG. 4 shows a flowchart of the method according to the invention for dispersing an aromatic prepolymer with continuous chain extension. FIG. 5 shows a further preferred embodiment of the mixing nozzle used to produce the pre-emulsion. FIG. 6 shows one embodiment of the method according to the invention for dispersing aliphatic prepolymers with continuous chain extension.

Claims (4)

a) A step of producing an aqueous pre-emulsion by mixing a polyurethane prepolymer containing a hydrophilic group and / or a latent hydrophilic group and water with a mixing nozzle, wherein the polyurethane prepolymer is put into water. And b) a multi-stage homogenizing nozzle having 2 to 20 nozzles and / or a disperser, comprising homogenizing the pre-emulsion from step a) to form an emulsion, at least A process for the continuous production of aqueous polyurethane dispersions based on one aliphatic and / or aromatic polyisocyanate.   The process according to claim 1, further comprising the step c) of reacting at least partially the emulsion comprising free NCO groups from step b) with at least one amine reactive towards isocyanate groups. Method.   The process according to claim 1, wherein a jet disperser is used as the homogenizing nozzle in step b).   The process according to claim 1, wherein the temperature of the water in step a) is 5 ° C to 95 ° C.

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